// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef CONTENT_PUBLIC_CHILD_WORKER_THREAD_H_
#define CONTENT_PUBLIC_CHILD_WORKER_THREAD_H_

#include "base/callback.h"
#include "base/macros.h"
#include "content/common/content_export.h"

namespace content {

// Utility functions for worker threads, for example service worker threads.
//
// This allows getting the thread IDs for service worker threads, then later
// posting tasks back to them.
class CONTENT_EXPORT WorkerThread {
public:
    // Observes worker thread lifetime.
    class CONTENT_EXPORT Observer {
    public:
        virtual ~Observer() { }

        // Notifies the observer that the current worker thread is about to be
        // stopped.
        //
        // The worker state may have already been destroyed. To observe that, use
        // ContentRendererClient::WillDestroyServiceWorkerContextOnWorkerThread.
        virtual void WillStopCurrentWorkerThread() { }
    };

    // Adds/removes an Observer. Observers are stored per-thread, so it is only
    // valid to call these from a worker thread, and events will be dispatched on
    // that worker's thread.
    static void AddObserver(Observer* observer);
    static void RemoveObserver(Observer* observer);

    // Returns the thread ID for the current worker thread, or 0 if this is not a
    // worker thread (for example, the render thread). Worker thread IDs will
    // always be > 0.
    static int GetCurrentId();

    // Posts a task to the worker thread with ID |id|. ID must be > 0.
    static void PostTask(int id, const base::Closure& task);

private:
    WorkerThread() {};
    DISALLOW_COPY_AND_ASSIGN(WorkerThread);
};

} // namespace content

#endif // CONTENT_PUBLIC_CHILD_WORKER_THREAD_H_
